1. Field of the Invention
This invention relates to image pickup devices, and more particularly to image pickup devices suited for video cameras.
2. Description of the Prior Art
Video cameras and like imaging apparatus utilizing solid state image sensing arrangements, generally avoid a dark current in the solid state image sensing by providing is generally adopted that a light-shielded area in a portion of an image pickup surface of the solid state image sensing arrangement. A signal obtained from this light-shielded area forms a reference of optical black (i.e., a black reference signal).
Up-to-date semiconductor techniques do not allow the number of picture elements in the horizontal line of a solid state image sensing arrangements to reach a level necessary to make the obtained image quality acceptable. Therefore, the number of picture elements which are assigned to the light-shielded area must be made as small as possible. As a result, prior art devices in which many picture elements had to be assigned to the light-shielded area suffered from a low resolution and a low productivity in mass fabrication of such image sensing means.